1. Technical Field
The present invention relates to an ion exchange membrane electrolyzer, and particularly to an ion exchange membrane electrolyzer capable of maintaining the gap between electrodes at a predetermined extent.
2. Related Art
In an electrolyzer used for electrolyzing aqueous solutions, the voltage required for electrolysis depends on various factors. In particular, the gap between anode and cathode has a large effect on the voltage of the electrolyzer. So, there are taken measures of reducing the gap between the electrodes to lower the voltage of the electrolyzer, thereby reducing consumption of the energy required for electrolysis.
In an ion exchange membrane electrolyzer used for electrolyzing a brine, the voltage of the electrolyzer is lowered by arranging three elements of anode, ion exchange membrane and cathode in close contact with one another. However, in a large electrolyzer provided with electrodes having an area of several square meters respectively, in case where the anode and cathode are connected to an electrode chamber by a rigid member, it has been difficult to reduce the gap between the electrodes to maintain the gap at a predetermined value by bringing both electrodes into close contact with an ion exchange membrane.
So, there is proposed an electrolyzer capable of adjusting the gap between the electrodes by using a flexible member for at least either of the anode or cathode. For example, there are proposed electrodes in each of which a flexible member comprising metallic fine wire woven fabric, unwoven fabric, net or the like is arranged on a porous electrode substrate.
Since the flexible members of these electrodes comprises metallic fine wires, there have been problems that the gap between the electrodes becomes uneven due to a partially deformed portion of an electrode and that the fine wires stick into an ion exchange membrane if the electrode is pushed excessively by the back pressure of a counter electrode chamber.
Moreover, there are proposed electrolyzers in which conductive connections are formed between the partition side of an electrode chamber and the electrodes by means of many plate-like spring materials. These electrolyzers are disclosed in, for example, JP-A-57-108278 and JP-A-58-37183.
Flexible electrodes using plate spring bodies exhibit better behaviors against partial deformations when being pushed than electrodes using members comprising fine wires, however, in these electrolyzers the plate spring bodies extend from a flexible cathode holding member obliquely only in the same direction.
Accordingly, if any force is exerted from an electrode plane side, on the electrode planes there is exerted force moving in one direction in which the spring materials are deformed due to the displacement of the plate spring bodies. As a result, the electrodes coming into contact with the plate spring bodies can be displaced, or an ion exchange membrane can be damaged in the displacement of the electrodes if the ion exchange membrane is in contact with the electrodes.
Then, in order to solve such problems, the present inventor proposes an ion exchange membrane electrolyzer capable of maintaining the gap to the counter electrode at a predetermined extent without the lateral displacement of the electrodes even if the electrode planes are pushed onto the plate spring bodies by arranging plates provided with plate spring bodies on a plate-like electrode chamber partition, a collector and the like and by mutually inserting comb-like opposed plate spring bodies into one another. Such an electrolyzer is disclosed in, for example, Japanese Patent No. 3501453.
It is an object of the present invention to provide an ion exchange membrane electrolyzer that can be easily assembled, has a high assembly precision and causes no lateral displacement of the electrodes coming into contact with the plate spring bodies, in which plates provided with plate spring bodies are arranged on a plate-like electrode chamber partition, collector and the like and comb-like mutually opposed plate spring bodies are inserted into one another.